cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A114425 Product of the first n 3-almost primes (A014612).

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%I A114425 #10 Apr 26 2020 13:32:26
%S A114425 8,96,1728,34560,933120,26127360,783820800,32920473600,1448500838400,
%T A114425 65182537728000,3259126886400000,169474598092800000,
%U A114425 10676899679846400000,704675378869862400000,47917925763150643200000
%N A114425 Product of the first n 3-almost primes (A014612).
%C A114425 3-almost prime analog of primorial (A002110). The semiprime analog of primorial is A112141. Equivalent for product of what A086062 is for sum. Bigomega(a(n)) = the number of not necessarily distinct prime factors of a(n) = A001222(a(n)) = A008585(n) = 3*n.
%H A114425 Harvey P. Dale, <a href="/A114425/b114425.txt">Table of n, a(n) for n = 1..364</a>
%F A114425 a(n) = Prod[from i = 1 to n] A014612(i).
%e A114425 a(5) = 933120 = 8 * 12 * 18 * 20 * 27 = the product of the first 5 values of the 3-almost primes = 2^8 * 3^6 * 5, which has 3*5 = 15 prime factors (with multiplicity).
%e A114425 a(20) = 137199755075271237225676800000000 = 8 * 12 * 18 * 20 * 27 * 28 * 30 * 42 * 44 * 45 * 50 * 52 * 63 * 66 * 68 * 70 * 75 * 76 * 78 * 92 = 2^26 * 3^15 * 5^8 * 7^4 * 11, which has 20*3 = 60 prime factors (with multiplicity).
%t A114425 FoldList[Times,Select[Range[70],PrimeOmega[#]==3&]] (* _Harvey P. Dale_, Apr 26 2020 *)
%Y A114425 Cf. A002110, A008585, A014612, A086062, A112141.
%K A114425 easy,nonn
%O A114425 1,1
%A A114425 _Jonathan Vos Post_, Feb 13 2006